In a TOF sensor, a light source emits light towards a scene. A time-of-flight detection pixel, or TOF pixel, of the sensor receives the light reflected by a point of the scene associated with this pixel. The measurement of the time of flight, that is, of the time taken by the light to travel from the light source to the point of the scene having the pixel associated therewith, and from this point back to the pixel, enables the distance separating the pixel from this point to be calculated.
In the case where a three-dimensional image of a scene is desired to be obtained, the TOF sensor comprises an array of TOF pixels for measuring the distance separating each pixel from the point of the scene having the pixel associated therewith. This provides a mapping of the distances separating the sensor from the different points of the scene having the pixels associated therewith, and a three-dimensional image of the scene can then be reconstructed from such a distance mapping. However, existing TOF pixels have relatively large dimensions. For example, a TOF pixel comprising a SPAD-type photodiode (“Single Photon Avalanche Diode”) may have a surface area in the order of 30 μm*30 μm.
It would be desirable to provide a TOF pixel overcoming at least some of the disadvantages of existing TOF pixels. For example, it would be desirable to provide a TOF pixel having a surface area smaller than 10 μm*10 μm, and for example smaller than 5 μm*5 μm.